Cheap Zigbee CO2 sensors any good?

Hey,
I´m moving into a new home that is equipped with a central ventilation system and I am going to control it via HA. Goal is to set values for Humidity and CO2. At first I thought about the MH-Z1X ESP route but now I´ve just discovered pretty cheap ready to use units on Ali.
I find it somehow strange that these devices are cheaper than a DIY CO2 module and I´d guess that they are not that accurate but as long as they are +/-100 ppm I´m fine with it.
Any experience? Maybe someone already verified the accuracy of those things.

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The world of sensors and the quality of the data they provide is a real wild west! I’ve spend too much time and money trying to ‘get a good solution’ in many sensor domains, and I am pretty sure I continue to be far from a solution.

That said, at my current state (read that as drawer full of devices).

For CO2, I am using the Aranet4 bluetooth units, link below. They are pricey, but on my rant, they defend their solutions with at least some research.

For temperature and humidity, I have stayed in the ‘low cost zone’ and have found that Bluetooth Low Energy devices that report ‘often’ seem to be the best route. Example device below.

Among the challenges is finding product that you can still buy, the changes in the availability of these low cost devices is a really challenge. If you find something that ‘works’, quickly buy a number of them to allow your project to run for a while. This is often a problem. I have some very good devices, that are no longer sold.

So my input based on my experience:

  1. Companies that will defend their solutions with some effort in the research front. This comment is ‘tongue and cheek’, however perhaps some strong reality… when you ‘take the cover off’ all these devices and find the same sensor, you have to question your cost vs. quality decisions soooooo much! However, so far, what I am using, I continue to think I have made good choices.

  2. Ease of getting the data from the sensor in a open aka ‘hackable’ way. Bluetooth so far is the winner here.

  3. Device readings update rate. This is a real ‘black box’ for many sensors. So far again, many Bluetooth Low energy devices seems to come out on top here.

  4. Battery life. From my experience, devices that are not ‘plugged into the wall’. Bluetooth devices win, because they last a long time, use low cost and powerful batteries and do not emphasize lasting for say 50 years vs. sending data at ‘useful’ intervals (a zigbee problem for home automation projects)

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My work, that continues to work for 2 years…however there are a number of BLE sensor collection projects that as well seem to be working very well:

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From another pov… the idea behind CO2 sensors is to protect you against…well … you guessed it. Connectivity to any (!) system should be sub to that. My main question (living in France) is… which of the dozens of offerings is actually working as designed. I bought 2, one triggered for whatever reason multiple times and had to throw it away…the other one did not trigger so far…but that raises a question : is it actually doing something?? I second the "wild west’ comment above and before all, regardless of where you want to connect it to, it should protect you … no bother discussing after you died :slight_smile:

It might take some effort to die from a high level of CO2. @vingerha are you confusing CO and CO2? Different problems.

Indeed…meant CO… so applicable comment but not in this topic :slight_smile:

@daKazze, the following may answer your question? The quality of the CO2 “guestimations” seems very poor: Notes on Tuya Air Quality Sensors (Electronics, Home Automation) — Kaspars Dambis

I know this post is pretty old, but for anyone coming here with the same question, CO2 sensors MUST have a NDIR sensor inside for an accurate measure, any other CO2 sensors are just crap estimations that are basically useless

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Indeed, this is an old topic, but I can’t leave this statement unanswered.

Have you ever measured CO₂ levels in your home? You might not die from CO₂ intoxication, but above 1000 ppm, more sensitive individuals can start experiencing unexplained headaches and fatigue. For others, symptoms may not appear until around 3000 ppm.

At 5000 ppm, CO₂ becomes a real concern for some and a significant discomfort for many.

In my well-sealed home, I have an MVHR system. The gap below the doors was supposed to allow proper airflow between rooms, but in practice, it doesn’t. At one point, I had a visitor staying in a room for several weeks. With the door and window closed, he started coughing and feeling short of breath after just one hour in bed.

I then bought a Netatmo station and discovered that CO₂ levels were rising to 7000 ppm.

CO₂ builds up in a closed space, creating an unhealthy environment. While oxygen levels remain mostly unchanged, excess CO₂ makes breathing more difficult and causes symptoms like headaches, dizziness, and shortness of breath. Without proper ventilation, the effects can go unnoticed—unless you’re aware of the issue and monitoring it.

I’m planning to buy a van, and I will definitely have a CO₂ sensor there, just as I always make sure to keep CO₂ levels below 2500–3000 ppm overnight where I sleep.

“Have you ever measured CO₂ levels in your home?”

Yes, I do. This was the topic of this thread I believe.

Just sayin’, based on my measurement over several years, if your value are above 800 or so, you have pretty poor air quality.

If your ‘van is down by the river’ and you are going to be happy with reading like this :

‘I’m planning to buy a van, and I will definitely have a CO₂ sensor there, just as I always make sure to keep CO₂ levels below 2500–3000 ppm overnight where I sleep.’

you might want do a bit more research on ways to get it down well below 1000 IMHO.

Good sleeping!

i’m curious where you measure the level of CO2 ?

I was in shock when I discovered this issue in my house (it was many years ago now). In most situation, there is a CO2 sensor on the outgoing air flow, but this shows the average for the whole house, and not a specific room. This is not reliable.

In my new flat, I still have the same problem. My lounge is never about 800ppm, however my room and my veranda (the lounge is in the middle, windowless), it rise up to 2500 and more. Even with the door open.

My feeling is this is not an uncommon issue in many recent well-sealed or well-insulated houses and flat, and most probably most people just don’t know and try to find plenty of reasons why their sleep give them not enough rest.

Anyway. You message sounded like CO2 is not a problem. I wanted to clarify that it can be, and it’s a good idea to monitor it.

“i’m curious where you measure the level of CO2 ?”

Sleeping and Living areas.

Good that you are monitoring CO2 levels, understanding their values over time and causes of change are very useful to better health outcomes IMHO. Not sure where you got this idea if you read through the thread :

‘You message sounded like CO2 is not a problem.’

Have a look this post I made ‘way back’ about the Aranet4 devices I have been using and why to shop carefully for devices that you trust for health and safety related DIY home automation.

While excessive CO and CO2 are not good for human health, their modality of action is very different.

Good hunting!